A Decade-Old Beer Is Gross, Right? Wrong.

Not necessarily! The chemistry behind aging ales, wet-cardboard taste, and what you can do about it.

Beer producers make a big deal about drinking beer fresh. Stone Brewery produces an IPA with a drink-by date. Russian River Brewing Company implores their customers right on the bottle label to drink Pliny the Elder fresh. And most other beer producers print the brewing date on the can or bottle so the customer knows he or she isn’t getting old beer. While it’s true that many (and perhaps most) beers taste better when fresh, it’s a fallacy that old beer always equals bad beer. Some breweries specifically make beer that needs to be aged for ten years or longer before it tastes right.

Beersci Logo Todd Detwiler

If you’re hesitant to drink a decade-old beer, you have good reason. Oxygen is most responsible for causing beer flavors to go awry over a long period of time. Charles Bamforth, a professor of Food Science and Technology at UC Davis, explains that oxygen causes the fatty acids in the beer to oxidize and form a multitude of chemicals, including nonenal, one of the main chemicals that contribute to the wet-cardboard flavor of beer past its prime. Nonenal isn’t the only culprit though. According to Bamforth, “Tens, if not hundreds, of types of molecules will contribute to the aging process.”

Brewers have done a good job at keeping oxygen out of their bottles. They apply a vacuum to each bottle and flush it with carbon dioxide in order to remove as much oxygen as possible before filling it with beer. Yet they still have other contaminants to worry about. “Traces of iron and copper can be picked up from the beer’s raw materials or the brewing equipment and can activate oxygen species as well,” says Bamforth.